All About Dams
Dams across the United States provide vital functions that many citizens depend upon daily. These include flood control, drinking water, irrigation, inland navigation (locks), and the generation of clean electricity. As a built structure that alters the flow of a river, retains copious amounts of water, and fragments river systems, dams are inherently vulnerable structures. The United States Army Corp of Engineers keeps track of all the dams across the country with the National Inventory of Dams.
A Few Dam Facts
Here is everything you want to know about the nation's dams at a glance.
- Dams are primarily constructed of concrete, steel, masonry, earth and rocks.
- Dams are typically categorized by:
- Type of construction, i.e., earthen or embankment.
- How the design holds back water, i.e., buttress, arch/half circle.
- According to its purpose, i.e., mill dams, electricity, or irrigation.
- The most prevalent dam type is the embankment/earthen dam
- There are more than 74,000 of embankment/earthen dams across the nation
National Dam Statistics Regarding Ownership, Operation, and Regulation
- Number of dams in the nation: 84,000.
- Average dam age: 52 years old (although some are more than 100 years old).
- Only 4% of dams are owned and maintained by the federal government.
- About 80% of dams are regulated by states.
- Alabama currently does not have any state dam regulations.
- The U. S. Army Corps of Engineers owns 694 dams.
- Only 2.5% of dams are owned and maintained by public utility companies.
- Approximately 58% of dams are privately owned and maintained.
- About 33% of dams were built for recreational purposes.
- About 17% of dams were constructed for flood control.
- Approximately 10% of the power in the United States is produced by federal hydro-electric dams.
National Dam Infrastructure Statistics
- 12,000+ dams are classified as significant hazards.
- 14,000+ dams are classified as high-hazard dams.
- 4,000+ dams failed inspection in 2013.
- 2,000 of those 4,000+ dams that failed inspection are classified as high-hazard.
- 170+ dam failures occurred between 2005 and 2013.
- 587 dams required rapid intervention to prevent a likely failure.
To provide a clear picture of what this means, a significant-hazard dam is one that would cause extensive property loss and likely have economic repercussions, while a high-hazard dam means there is a high probability of human fatalities if a failure should occur.
A few recent failures:
The Kaloko Reservoir Dam failure in Kilauea, Hawaii, 2006:
- Privately Owned Dam
- Killed 7 People
- Nearly 400 million gallons of water released
The Big Bay Lake Dam failure in Jackson, Mississippi, 2004:
- 48 Homes destroyed
- 56 Homes and Businesses Damaged
- 30 Roads Damaged or Closed
The Silver Lake Dam failure near Marquette, Michigan, 2003:
- $100 Million in damages
- 1,000+ miners temporarily out of work
- 2 dams failed, but 2 lower dams held, preventing loss of life